A strain of Bacillus mobilis XH-5 and its application

Abstract

The present invention discloses a strain of Bacillus mobilis XH-5 and its application, belonging to the field of microorganisms. The present invention provides a strain of Bacillus mobilis XH-5, whose deposit number is CGMCC No.31550. The strain can tolerate 60gL ‑1 The bacterium can survive in a saline-alkali environment of 100 mM NaCl and pH=10, and has the potential plant growth-promoting ability such as producing IAA and iron carriers; the bacterium can improve the germination rate of rice / tomato seeds under NaCl stress; the strain is inoculated into the rhizosphere of potted corn, and can improve the growth index of corn under 700 mM NaCl stress. The present invention is of great significance to improving the microecological environment of saline-alkali soil, improving plant salt tolerance and yield, promoting the efficient utilization of saline-alkali land resources, promoting green and sustainable development of agriculture, and providing guarantee for food security.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural biological product production, and in particular to a rhizosphere growth-promoting bacterium capable of enhancing the salt tolerance of crops. Background Art

[0002] The total area of ​​saline-alkali land in my country is as high as 36.9 million hm2. 2 , accounting for about 5% of the country's available land area, of which saline-alkali arable land accounts for about 7.6 million hm 2 . Soil salinization not only causes soil compaction and decreased fertility, hindering plants from absorbing nutrients, but also affects the physiological processes of plants through osmotic stress and ionic stress, inhibits seed germination and rooting, increases plant growth energy consumption, thereby accelerating plant aging, and ultimately causing plant wilting or death. Due to droughts, reduced precipitation and rising temperatures caused by global climate change, coupled with unreasonable agricultural irrigation measures (such as imperfect drainage systems and excessive irrigation), soil salt accumulation has become increasingly severe, and the area of ​​saline-alkali land has continued to expand, posing severe challenges to agricultural production and the ecological environment. Therefore, the rational use and improvement of saline-alkali land and the improvement of crop productivity have become one of the key topics in agricultural research in my country and even the world.

[0003] Plant Growth-Promoting Rhizobacteria (PGPR) are a type of beneficial microorganisms that colonize the rhizosphere of plants. They have attracted widespread attention because they can promote plant growth and improve plant resistance to adverse environmental stresses through a variety of mechanisms. First, PGPR stimulates the growth and development of plant roots by secreting auxins (such as IAA) and enhances the plant's ability to absorb water and nutrients. Second, PGPR enhances the plant's absorption of trace elements by producing iron carriers and has an advantage in competing with pathogens for iron, thereby inhibiting the growth of pathogens. Then, PGPR can help plants maintain cellular water balance in a high-salt environment by regulating the accumulation of osmotic regulating substances (such as proline and soluble sugars), thereby enhancing the plant's salt tolerance. Finally, PGPR can activate the plant's antioxidant enzyme system, such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD), effectively reducing the accumulation of reactive oxygen species, thereby alleviating the oxidative stress response caused by salt stress and protecting plant cells from damage.

[0004] With the deepening of PGPR research, more and more strains with excellent growth-promoting ability and salt resistance have been screened and successfully applied to saline-alkali land improvement. These strains can help plants maintain normal growth under saline-alkali stress, improve the salt tolerance and yield of crops, and are important microbial resources for improving saline-alkali land crop production. PGPR-based microbial agents have the advantages of low cost, environmental protection, and easy operation. They show broad application prospects in agricultural production and are of great significance to promoting sustainable agricultural development, promoting green agricultural transformation, and ensuring food security. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a strain capable of enhancing the salt stress tolerance of crops, thereby increasing the biomass of crops under salt stress environment and promoting the effective development and utilization of saline-alkali land.

[0006] The technical solution of the present invention is: a strain of Bacillus mobilis XH-5, which was deposited in the General Microbiology Center of China Microorganism Culture Collection Committee (referred to as CGMCC; address: No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; Postal Code: 100101) on August 5, 2024, and the deposit number is CGMCC No. 31550.

[0007] A microbial preparation containing the above-mentioned Bacillus mobilis XH-5.

[0008] The application of the above-mentioned Bacillus mobilis XH-5 or microbial preparation in improving the germination rate of plant seeds in a salt stress environment.

[0009] Furthermore, the plant seeds are rice or tomatoes.

[0010] Furthermore, when the plant seeds are rice, Bacillus mobilis XH-5 is added at 10 6 ~10 7 CFU / ml concentration was inoculated into rice seeds.

[0011] Furthermore, when the plant seeds are tomatoes, Bacillus mobilis XH-5 is added at 10 7 CFU / ml concentration inoculated tomato seeds.

[0012] The use of the above-mentioned Bacillus mobilis XH-5 or microbial preparation in improving the salt tolerance of plants.

[0013] The application of the above-mentioned Bacillus mobilis XH-5 or microbial preparation in increasing the biomass of plants in a salt stress environment.

[0014] Furthermore, the plant is corn.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention provides a strain capable of improving the salt stress tolerance of plants (rice, tomato and corn), and the strain can tolerate 60g L -1 It can adapt to the saline-alkali environment of NaCl and pH=10, and has the potential plant growth-promoting ability such as producing IAA and siderophores, and is a rhizosphere growth-promoting bacterium. The strain can improve the germination rate and average root length of rice and tomato seeds under salt stress; can significantly reduce the malondialdehyde (MDA) content, catalase (CAT) activity, peroxidase (POD) activity and superoxide dismutase (SOD) activity in young tomato roots; when the bacteria is inoculated into the roots of potted corn, it can significantly improve the growth indicators of corn (fresh weight and dry weight, etc.) under high salt stress; significantly increase the proline (Pro) and soluble sugar content in the aboveground part of corn, and significantly increase the proline (Pro) content in the underground part of corn; significantly reduce the malondialdehyde (MDA) content in the aboveground part of corn, and significantly increase the catalase (CAT) activity, peroxidase (POD) activity and superoxide dismutase (SOD) activity in the aboveground part of corn; significantly reduce the malondialdehyde (MDA) content, catalase (CAT) activity and superoxide dismutase (SOD) activity in the underground part of corn.

[0017] Collection information:

[0018] Bacillus mobilis XH-5 was deposited in the General Microbiology Center of China Microorganism Culture Collection Committee (CGMCC for short; address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; Postal Code: 100101) on August 5, 2024, with the deposit number CGMCC No.31550. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The following are photos of strain colonies and cell phenotypes.

[0020] Figure 2 Growth curve of strains was determined.

[0021] Figure 3 To test the salt and alkali tolerance of the strain.

[0022] Figure 4 To test the biofilm forming ability of strains.

[0023] Figure 5 It is the rice seed growth index under different treatments in the strain-promoted salt-tolerance germination test in Example 3.

[0024] Figure 6 It is the tomato seed growth index under different treatments in the strain-promoted salt-tolerance germination test in Example 3.

[0025] Figure 7 These are the MDA content and antioxidant enzyme activity-related indicators of young roots of tomato seeds under different treatments in the strain-promoted salt-tolerance germination test in Example 3.

[0026] Figure 8 These are the phenotypic photos and growth indicators of corn under different treatments in the salt tolerance pot experiment in Example 4.

[0027] Fig. 9 It is the osmotic substance content of corn under different treatments in the salt tolerance pot experiment in Example 4.

[0028] Fig.10 These are the MDA content and antioxidant enzyme activity related indicators of corn under different treatments in the salt tolerance pot experiment in Example 4. DETAILED DESCRIPTION

[0029] The experimental methods in the following examples are all conventional methods unless otherwise specified. The experimental materials used in the following examples are all purchased from commercial channels unless otherwise specified.

[0030] The quantitative tests in the following examples were repeated more than three times, and the results were averaged.

[0031] Rice variety Nanjing 46: Available from various fruiting stores and online stores.

[0032] Tomato variety Cooperation 903: Available from various fruit stores and online stores.

[0033] Corn variety Mingyu 1203: Available from various physical stores and online stores.

[0034] Example 1. Strain origin, morphology, growth ability test and preservation

[0035] 1. Sample collection and strain isolation

[0036] Rhizosphere soil of Qinghai desert halophytes was collected, the soil suspension was gradient diluted, and a suitable gradient was selected to be spread on TSB medium and cultured at 30°C overnight. The strains on the plate were separated and purified, and strain XH-5 was screened.

[0037] 2. Molecular identification of strain XH-5

[0038] The 16S rDNA sequence of strain XH-5 was amplified and sequenced, and the sequencing result is shown in Sequence 1 of the sequence table. After identification, it can be determined that strain XH-5 belongs to Bacillus mobilis, referred to as Bacillus XH-5.

[0039] 3. Morphological observation of Bacillus XH-5

[0040] 1. Colony phenotype observation

[0041] Use an inoculation loop to dip the strain storage solution of Bacillus XH-5 in the glycerol tube, streak on the TSB solid plate, place it in a 30℃ biochemical incubator for constant temperature culture and activation until a single colony grows, take pictures and record the colony phenotype. Figure 1 As shown in A, the colonies of Bacillus XH-5 are round, have wavy edges, are milky white, have radial wrinkles on the surface, and have a sticky texture.

[0042] 2. Cell phenotype observation

[0043] 2.1. Strain preparation: After activating Bacillus XH-5, take 1% of the inoculum into TSB liquid culture medium and culture at 30°C and 200 rpm for 1 day.

[0044] 2.2. Sample preparation:

[0045] (1) Pre-fixation: fix in 2.5% glutaraldehyde solution at 4°C overnight;

[0046] (2) Rinsing: Pour off the fixative solution and rinse the sample three times with 0.1 M phosphate buffer (pH = 7.0), each time for 15 min;

[0047] (3) Refixation: Fix the sample with 1% osmium acid solution for 1-2 hours;

[0048] (4) Rinsing: Pour off the fixative solution and rinse the sample three times with 0.1 M phosphate buffer (pH = 7.0), each time for 15 min;

[0049] (5) Dehydration: The samples were dehydrated with ethanol solutions of gradient concentrations (including 50%, 70%, 80%, 90% and 95%), with each concentration treated for 15 min; then treated twice with 100% ethanol, each time for 20 min;

[0050] (6) Overtreatment: Treat the sample with a mixture of ethanol and isoamyl acetate (V / V = 1 / 1) for 30 min, and then treat the sample with pure isoamyl acetate for 1-2 h;

[0051] (7) Critical point drying;

[0052] (8) Coating and observation.

[0053] 2.3. Electron microscopy: Use Hitachi 8100 electron microscope to observe and take photos of the strain morphology.

[0054] Electron microscopy results of Bacillus XH-5 are as follows Figure 1 As shown in B, the cells are about 3 μm in diameter, short rod-shaped, with a rough surface and uniform cell morphology.

[0055] 4. Growth ability test of strains

[0056] 1. Use an inoculation loop to dip the Bacillus XH-5 preservation solution in the glycerol tube, streak it on the TSB solid plate, and place it in a 30℃ biochemical incubator for constant temperature culture and activation until a single colony grows.

[0057] 2. Use a sterile pipette tip to pick up a single colony, inoculate it into a test tube containing 3 mL of TSB liquid culture medium, and culture it in a 30°C constant temperature shaker for 24 hours to prepare the seed solution.

[0058] 3. Inoculate the seed solution into fresh TSB liquid medium at a 1% inoculum volume, and dispense 200 μL per well into a sterile 100-well plate dedicated to the bacterial automatic growth curve analyzer. Place the well plate in the instrument, culture at 30°C, and measure the OD every 60 minutes. 600 The value was measured, shaken for 30 seconds before and after the measurement, and cultured for 25 hours to complete the growth test of the bacteria throughout the entire cycle. Three wells were set up for replication, and a blank TSB medium without strain seed solution was used as a control. After the experiment, the data was exported and Excel and Origin software were used for data analysis and chart drawing.

[0059] Specific results such as Figure 2 As shown, the growth curve of strain XH-5 is S-shaped, with 0-2h as the lag phase, 2-10h as the logarithmic growth phase, and reaching the plateau phase after 10h. The strain has a short lag phase, grows rapidly, can reach a high population density in the plateau phase, is easy to culture, and is convenient for liquid fermentation of microbial agents.

[0060] V. Preservation of Bacillus XH-5

[0061] The Bacillus mobilis XH-5 provided by the present invention has been deposited in the General Microbiological Center of China Microbiological Culture Collection Committee (referred to as CGMCC; address: No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; Postal Code: 100101), and the deposit number is CGMCC No.31550.

[0062] Example 2: Test of plant growth-promoting related indicators of Bacillus XH-5

[0063] 1. Test of salt and alkali resistance

[0064] a. Salt tolerance test

[0065] The seed solution of Bacillus XH-5 was prepared by the method in Example 1, and inoculated at a 1% inoculum into 5, 20, 40, 60, 80, 100, and 120 g L -1 The culture medium was freshly prepared and dispensed into a 96-well plate at 200 μL per well. The plate was placed in a 30°C, 200 rpm shaking incubator. After 48 h, the OD value of the bacterial solution was measured using an ELISA reader. 600 Data analysis and graph drawing were performed using Excel and Prism software.

[0066] b. Alkali resistance test

[0067] The seed solution of Bacillus XH-5 was prepared by the method in Example 1, and inoculated into fresh TSB medium with pH values ​​of 6, 7, 8, 9, 10, and 11 at a 1% inoculation amount, and dispensed into 96-well plates at 200 μL per well. The well plates were placed at 30°C and 200 rpm for shaking culture. After 48 h, the OD value of the bacterial solution was measured using an ELISA reader. 600 Data analysis and graph drawing were performed using Excel and Prism software.

[0068] Specific results such as Figure 3 The results showed that Bacillus XH-5 had the ability to tolerate 60 g L -1 The ability to survive in a strong alkaline environment of NaCl and pH=10 can ensure the normal survival of Bacillus XH-5 in saline-alkali environments and the stable performance of its plant growth-promoting function.

[0069] 2. IAA production capacity determination

[0070] Bacillus XH-5 was inoculated in a medium containing 1 g L -1 The culture medium was incubated in Landy medium containing L-tryptophan at 30°C and 200 rpm for 72 hours, and 1 mL of the culture solution was centrifuged at 12,000 rpm for 5 minutes to obtain the supernatant, which was then assayed using an Elisa kit (enzyme immunosorbent assay) to calculate the IAA production (nmol / L) of Bacillus XH-5.

[0071] IAA (Indole-3-Acetic Acid) is one of the important auxins in plants and plays a key role in plant growth and development. IAA significantly improves the salt tolerance of plants under salt stress by promoting root development, regulating ion balance, enhancing osmotic regulation and improving antioxidant capacity. It not only helps plants effectively cope with salt toxicity, but also maintains normal growth and development of plants in adversity, and is therefore regarded as one of the important growth-promoting characteristics of the strain. The results showed that the IAA production of Bacillus XH-5 could reach 13.18±0.54nmol / L, indicating that it has a certain potential to promote plant growth.

[0072] 2. Determination of iron carrier production capacity

[0073] The seed liquid of Bacillus XH-5 was prepared by the method in Example 1, and inoculated into TSB liquid medium at a 1% inoculum, cultured at 30°C, 200 rpm for 24 h, centrifuged at 12000 rpm for 15 min, and the supernatant was sterilized by membrane, mixed with an equal volume of CAS detection solution, reacted fully, and the OD was measured. 630 , and the absorbance value As was obtained, and double distilled water was used as a control to adjust the value to zero; uninoculated culture medium and CAS detection solution were mixed in equal volumes, and OD was measured. 630 , and the absorbance value Ar was obtained. The As / Ar value represents the relative content of siderophore in the sample. The siderophore content determination was repeated 3 times. As / Ar ranged from 1.0 to 0 with an interval of 0.2. Every time As / Ar decreased by 0.2, a "+" was added. There were five levels from "+" to "+++++". The higher the level, the stronger the siderophore production ability of the strain.

[0074] CAS blue test solution formula: Solution A: Dissolve 60.5 mg CAS in 50 mL deionized water, add 10 mL FeCl 3 Solution (containing 1 mM FeCl 3 6H 2 O, 10mM HCl); Solution B: Dissolve 72.9mg HDTMA (hexadecyltrimethylammonium bromide) in 40mL deionized water; Slowly inject Solution A into Solution B along the wall of the beaker to obtain CAS blue detection solution.

[0075] Siderophores significantly improve the salt tolerance of plants under salt stress by enhancing iron absorption, improving antioxidant capacity, regulating hormone metabolism, reducing heavy metal toxicity, inhibiting pathogens, and promoting the symbiosis of beneficial microorganisms. Siderophores are important for maintaining healthy plant growth and enhancing their stress resistance in saline-alkali soils, and are an effective strategy to improve plant salt tolerance. The siderophore production capacity of Bacillus XH-5 is at the second level "++", indicating that it has a certain ability to produce siderophores, that is, it has potential plant growth-promoting function.

[0076] 3. Biofilm formation ability test

[0077] The seed solution of Bacillus XH-5 was prepared by the method in Example 1, and inoculated into a 48-well plate containing 1 mL of fresh TSB medium at a 1% inoculum. The plate was sealed with plastic wrap and statically cultured in a 30° C. biochemical incubator. The biofilm formation was observed at different time points and photographed and recorded.

[0078] The formation of biofilms provides a protective environment for the cooperative symbiosis of microorganisms and plants, and significantly improves the salt tolerance of plants through multiple mechanisms such as promoting the colonization of beneficial microorganisms, regulating nutrient and water acquisition, and alleviating salt stress and oxidative stress. Therefore, using plant growth-promoting bacteria with good biofilm formation ability to enhance plant salt tolerance is an important strategy in agricultural production and saline-alkali land improvement. Figure 4 Bacillus XH-5 does not have the ability to form biofilms, and it is speculated that it may not be able to colonize on the surface of plant roots, but may exert its plant growth-promoting function by releasing signal substances or entering the roots of plants.

[0079] Example 3: Test on promoting salt-tolerant germination of seeds by Bacillus XH-5

[0080] a. Preparation of bacterial suspension

[0081] After the strain was activated, it was inoculated into TSB liquid medium at a 1% inoculum and cultured at 30°C and 200 rpm. The supernatant was removed by centrifugation to collect the bacteria, and the bacteria were washed three times with sterile NaCl solution (250 mM for rice seeds and 100 mM for tomato seeds) to a final concentration of OD 600 =1(approximately 10 8 CFU / mL). The bacterial suspension at OD=1 was diluted with sterile NaCl solution (250 mM for rice seeds and 100 mM for tomato seeds) to obtain the test bacterial suspensions: original concentration bacterial suspension (XH-5_1), 10-fold diluted bacterial suspension (XH-5_2), and 100-fold diluted bacterial suspension (XH-5_3).

[0082] b. Seed treatment

[0083] Select an appropriate amount of rice / tomato seeds with full grains and comparable grain size, clean the surface dust with distilled water, soak them in 1% NaClO solution for 2 minutes, soak them in 75% alcohol for 5 minutes, rinse them with sterile deionized water for 5 to 7 times, and soak the sterilized rice / tomato seeds in sterile deionized water at room temperature for 24 hours for later use.

[0084] c. Germination test

[0085] Take 20 rice / tomato seeds and place them evenly in a 9 cm petri dish covered with two layers of filter paper. Five treatments were set up in the experiment: ddH2 O treatment (10 mL sterile ddHO 2 O), NaCl treatment [10mL sterile NaCl solution (250mM for rice seeds and 100mM for tomato seeds)], XH-5_1 treatment (10mL XH-5_1 bacterial suspension), XH-5_2 treatment (10mL XH-5_2 bacterial suspension), XH-5_3 treatment (10mL XH-5_3 bacterial suspension). Use a pipette to slowly inject the solution in the treatment into the edge of the culture dish (be careful to avoid the liquid directly impacting the seeds), and then shake the culture dish slightly to spread the solution evenly on the culture dish. Set up 3 replicates of each treatment, and place the culture dish in a light incubator (25°C, 80% RH) for culture until ddH 2 The germination rate of seeds in group O reached more than 90%. The experiment was ended and a series of data were recorded and measured, including germination rate, seed root length (seeds take root before germination, so the seed root length is counted), root MDA content and antioxidant enzyme activity (only the treatment group that can significantly improve seed germination rate and average root length, i.e., tomato XH-5_2 treatment and control group).

[0086] High-salt environment significantly inhibits plant seed germination by inducing osmotic stress, ion toxicity, accumulation of reactive oxygen species, nutritional metabolic disorders, hormone imbalance, and cell membrane damage. Long-term exposure to high-salt conditions will severely inhibit the germination rate, germination speed, and seedling growth of seeds, thereby affecting plant survival and yield. The Bacillus XH-5 shown can significantly alleviate the inhibition of high-salt environment on rice seed germination, and improve the germination rate and root length of rice seeds in high-salt environment ( Figure 5 ).

[0087] In addition, Bacillus XH-5 can significantly alleviate the inhibition of high-salt environment on tomato seed germination and improve the germination rate and root length of tomato seeds under salt stress ( Figure 6). Malondialdehyde (MDA) is a product of lipid peroxidation in plant cells and is often used as an important indicator to measure the degree of cell membrane damage and the level of oxidative stress. By measuring the content of MDA, the antioxidant defense ability and salt tolerance level of plants can be evaluated. Some PGPRs can reduce the accumulation of MDA in plants under salt stress, thereby reducing the damage of salt stress to cells. Inoculation with Bacillus XH-5 can significantly reduce the content of malondialdehyde (MDA) in young tomato roots, indicating that it can alleviate the damage of salt stress to tomatoes. Catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) can control the accumulation of reactive oxygen species through synergistic effects, maintain the structural stability and functional integrity of cells, and effectively cope with the oxidative stress caused by salt. The bacteria can significantly reduce the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in young tomato roots, indicating that the strain can enhance the antioxidant capacity of tomatoes and reduce oxidative stress damage by regulating the antioxidant enzyme system pathway, thereby promoting tomato seed germination and rooting ( Figure 7 ).

[0088] Example 4: Potted plant experiment on bacterial strains promoting salt tolerance growth

[0089] 1. After surface disinfection, sow Mingyu 1203 corn seeds in moist vermiculite and cultivate them in a glass greenhouse under natural conditions. Select seedlings with uniform growth at the cotyledon stage and transplant them into pots (1 L in volume, with a tray containing 800 mL of substrate) filled with seedling cultivation peat.

[0090] 2. 5 days after corn seedlings are transplanted, the potted plants are treated as follows:

[0091] H 2 Group O: Only tap water was added during the planting period, with 100 mL of tap water added every 3 days for a total of 10 times.

[0092] NaCl group: A total of 32.18 g NaCl was added (making the final salt concentration in the substrate about 700 mM), and each addition was made by pouring the salt solution into the root system. The experiment adopted the interval multi-frequency salt addition method: 100 mL of 550 mM NaCl solution was added every 3 days, for a total of 10 times.

[0093] NaCl+XH-5 group: In addition to the addition of NaCl as in the NaCl treatment group, the Dermococcus XH-5 was inoculated when the NaCl solution was first added, so that the final concentration of Dermococcus XH-5 was 1×10 7 CFU g -1 earth.

[0094] 3. The potted plants were cultured in the greenhouse for 6 weeks, and the growth indicators of corn plants (fresh weight, dry weight, plant height and root length), plant cell osmosis-related indicators (proline Pro content and soluble total sugar), plant oxidative damage and antioxidant enzyme system (MDA content, CAT activity, POD activity and SOD activity in the aboveground part, MDA content, CAT activity, POD activity and SOD activity in the underground part) were observed, recorded and measured. The MDA content, CAT activity, POD activity, SOD activity, proline (Pro) content and soluble total sugar in the aboveground and underground parts were measured using commercial kits (all purchased from Solebow Biotechnology Co., Ltd.). The determination method is detailed in the kit instructions. P is the P value, and FC (Fold Change) is the difference multiple.

[0095] The results showed that Bacillus XH-5 could improve the growth indexes of corn (fresh weight and dry weight, etc.) under salt stress and ensure the normal growth of corn ( Figure 8 ). It shows that Bacillus XH-5 has excellent growth-promoting ability for corn under extremely severe salt stress (700mM NaCl), ensuring the yield stability of corn in a high-salt environment, which provides a theoretical basis and application potential for the development of microbial growth promoters under salt stress environments.

[0096] Proline (Pro) and soluble sugars effectively improve the survival and adaptability of plants under salt stress through multiple mechanisms such as helping plants maintain cellular water balance, protecting proteins and cell membrane structures, and reducing the accumulation of reactive oxygen. Bacillus XH-5 can significantly increase the content of proline (Pro) and soluble sugars in the aboveground part of corn, and significantly increase the content of proline (Pro) in the underground part of corn. This shows that Bacillus XH-5 can enhance the osmotic regulation ability of plants and activate their antioxidant defense mechanisms, thereby improving stress resistance indicators, helping corn better adapt to salt stress, and ensuring its growth and yield, showing its application value as a potential microbial growth promoter ( Fig. 9 ).

[0097] Bacillus XH-5 can reduce the MDA content in the aboveground and underground parts of corn, and alleviate the damage of corn to salt stress. It can also significantly increase the activity of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in the aboveground part of corn; and significantly reduce the activity of catalase (CAT) and superoxide dismutase (SOD) in the underground part of corn. This shows that Bacillus XH-5 can alleviate the stress effect of corn plants under salt adversity by regulating the above three antioxidant enzyme systems ( Fig.10 ).

Claims

1. A strain of Bacillus mobilis ( Motile Bacillus )XH-5, the deposit number is CGMCC No. 31550.

2. A method comprising: comprising: containing the Bacillus mobilis according to claim 1 ( Motile Bacillus ) Microbial preparation of XH-5.

3. The Bacillus mobilis according to claim 1 ( Motile Bacillus ) Use of XH-5 or the microbial preparation described in claim 2 to improve the germination rate of plant seeds in a salt stress environment, wherein the plant seeds are rice or tomatoes.

4. The use according to claim 3, characterized in that When the plant seeds are rice, Bacillus mobilis ( Motile Bacillus )XH-5 with 10 6 ~10 7 CFU / ml concentration was inoculated into rice seeds.

5. The use according to claim 3, characterized in that: When the plant seeds are tomatoes, Bacillus mobilis ( Motile Bacillus )XH-5 with 10 7 CFU / ml concentration inoculated tomato seeds.

6. The Bacillus mobilis according to claim 1 ( Motile Bacillus ) Use of XH-5 or the microbial preparation described in claim 2 to improve the salt tolerance of corn.

7. The Bacillus mobilis according to claim 1 ( Motile Bacillus ) Use of XH-5 or the microbial preparation described in claim 2 to increase the biomass of corn in a salt stress environment.

Images